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Vocalisation of the Great Spotted Kiwi : an Assessment of Vocal Individuality

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Vocalisation of the Great Spotted Kiwi : an Assessment of Vocal Individuality Lincoln University Digital Dissertation Copyright Statement The digital copy of this dissertation is protected by the Copyright Act 1994 (New Zealand). This dissertation may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use: you will use the copy only for the purposes of research or private study you will recognise the author's right to be identified as the author of the dissertation and due acknowledgement will be made to the author where appropriate you will obtain the author's permission before publishing any material from the dissertation. Vocalisations of the Great Spotted Kiwi (Apteryx haastii): an Assessment of Vocal Individuality A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science (Honours) at Lincoln University by Jennifer May Dent Lincoln University 2013 Abstract of a dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science (Honours) Vocalisations of the Great Spotted Kiwi: an Assessment of Vocal Individuality by Jennifer May Dent Kiwi (Apteryx spp.) vocalisations are routinely used as part of a nationwide monitoring programme in which call-rate is used to infer population density. The ability to individually identify kiwi would drastically improve the accuracy and quality of monitoring programmes. One potential avennue to achieve this is through acoustic identification. In many vocally active species, vocalisations have been shown to encode information about the identity of the caller (vocal individuality). This has proven extremely useful in monitoring rare, nocturnal and cryptic bird species. In this study, vocal individuality was assessed with regard to a population of great spotted kiwi (Apteryx haastii) residing in the Hawdon Valley, Canterbury, New Zealand. Acoustic recorders were installed near the breeding den sites of seven great spotted kiwi pairs between November 2012 and March 2013. In total 303 whistle vocalisations were recorded during this time. A range of temporal and spectral parameters were measured from the highest quality recordings. These measurements were taken at a whole call and individual syllable level. Call parameters were; number of syllables, syllable rate and syllable duration. Syllable parameters were; minimum frequency (Hz), maximum frequency (Hz), bandwidth (Hz), duration (sec) and peak frequency (Hz). These variables were used to describe and classify calls using one-way repeated measures ANOVAs and stepwise discriminant function analysis. Male and female syllables are sexually dimorphic, however, the pattern of temporal and spectral variation within calls is consistent between sexes. Discriminant function analysis indicated that great spotted kiwi vocalisations were highly individualised. Male individuals were were classified with an accuracy of 95.7% on the basis of seven parameters. Females were classified with an accuracy of 90% on the basis of five call parameters. In both analyses spectral parameters were shown to be most important for individual discrimination. This is the highest degree of vocal individuality in Apteryx species reported to date. Such a high degree of individuality indicates that great spotted kiwi vocalisations could be utilised for individual identification purposes. The next step is to assess the temporal stability of this phenomenon. Keywords: vocal individuality, Apteryx haastii, Hawdon Valley, whistle call, fundamental frequency, autonomous acoustic recording, acoustic monitoring, call-rate, vocal dimorphism ii Acknowledgements I would like to express my gratitude to the following people, without whom this research would not be possible. Firstly I would like to thank my primary supervisor, Laura Molles for her guidance, support and enthusiasm throughout this process. I would also like to thank my co-supervisor James Ross for his assistance with the development of my dissertation. I would like to thank the Department of Conservation for allowing me access to the Hawdon Valley acoustic recordings. Special thanks to Sandy Yong and Kaitlin Morrison who were largely responsible for the deployment and maintenance of the DOC recording devices. Sandy and Kaitlin have also been tremendously helpful throughout the year whenever I required additional information. I would also like to thank James Ross and Cathy Mountier for their role in the collection of the acoustic recordings. All collection was conducted under the Department of Conservation research permit CA- 34889-RES. Last but not least, thank you to all of my friends and family; Mum, Dad, Nana and James for your constant love and support, Nixie, Astrid and Luke for forcing me to achieve some sort of work-life balance, and my office mate Megan Outram for helping me to see the funny side of life, even on the most stressful of days - our antics this year have kept me sane. iii Table of Contents Abstract ....................................................................................................................................... ii Acknowledgements ..................................................................................................................... iii List of Tables ............................................................................................................................... vi List of Figures ............................................................................................................................. vii Chapter 1 Literature Review.......................................................................................................... 1 1.1 General Introduction...................................................................................................................... 1 1.2 Great Spotted Kiwi ......................................................................................................................... 2 1.3 Species Status ................................................................................................................................ 4 1.3.1 Causes of Decline .............................................................................................................. 4 1.4 Conservation Effort ........................................................................................................................ 5 1.4.1 Management ..................................................................................................................... 5 1.4.2 Monitoring ........................................................................................................................ 6 1.5 Vocal Individuality .......................................................................................................................... 9 1.5.1 Assessing Vocal Individuality ........................................................................................... 10 1.5.2 Conservation Applications .............................................................................................. 11 1.5.3 Limitations ....................................................................................................................... 13 1.6 Kiwi Vocal Behaviour .................................................................................................................... 13 1.6.1 Kiwi Vocalisations ............................................................................................................ 13 1.6.2 Potential for Vocal Individuality ...................................................................................... 14 1.7 Research Objectives ..................................................................................................................... 15 Chapter 2 Methods and Materials ............................................................................................... 16 2.1 Study Area .................................................................................................................................... 16 2.2 Call Recording .............................................................................................................................. 17 2.3 Processing Recordings ................................................................................................................. 20 2.3.1 Extraction ........................................................................................................................ 20 2.3.2 Filtering ........................................................................................................................... 23 2.4 Call Measurement ........................................................................................................................ 23 2.5 Statistical Analysis ........................................................................................................................ 26 2.5.1 Descriptive Statistics ....................................................................................................... 26 2.5.2 Analysis of Variance ........................................................................................................ 26 2.5.3 Variable Assesment ......................................................................................................... 27 2.5.4 Discriminant Function Analysis ....................................................................................... 28 Chapter 3 Results .......................................................................................................................
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